Pediatrics

Acute Cerebellar Ataxia

OVERVIEW: What every practitioner needs to know

Acute cerebellar ataxia, also known as postinfectious cerebellitis, most often presents in younger children 2-6 years of age. It often presents weeks after a viral illness or more rarely after a recent vaccination.

Are you sure your patient has acute cerebellar ataxia? What are the typical findings for this disease?

The child is otherwise well but suddenly develops cerebellar signs, including imbalance and gait abnormalities. Other common symptoms may include the following: horizontal nystagmus, truncal and/or head titubation, dysarthria, and dysmetria. There is no fever or meningeal symptoms. The child will not be grossly encephalopathic but could have transient, nonspecific behavioral changes and difficulty concentrating.

Although the prognosis is very good for these children and more than 90% will make a full recovery, the recovery may take weeks to months from the onset of symptoms. If the child’s course does not improve or worsens, the search should continue for a different cause of the ataxia.

What other disease/condition shares some of these symptoms?

There are several causes of acute ataxia in children. One of the important distinguishing features of the ataxia is whether the symptoms are monophasic or intermittent. Because it may be difficult to ascertain if the symptoms are intermittent until future presentations, it is important to consider all possible causes for ataxia.

What caused this disease to develop at this time?

This disease is a postinfectious syndrome. Most often, the child had an illness weeks before developing the acute ataxia. The child often has evidence of an inflammatory process (but no current infection) in the cerebrospinal fluid with pleocytosis. The pertinent physical findings might include imbalance, gait ataxia, nystagmus, dysmetria, dysarthria, and behavioral changes.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

Acute cerebellar ataxia is a diagnosis of exclusion. Often, eliciting the history of a recent illness and the sudden onset of cerebellar findings without other neurologic changes raises the suspicion of acute cerebellar ataxia; however, because it often involves a young child, the examination and history may be limited. Therefore, further workup is often necessary.

A urine and/or serum toxicology screen is ordered to rule out ingestion/intoxication. A complete blood count (CBC) is ordered to evaluate for changes supportive of illness. A lumbar puncture (LP) is ordered to evaluate for infection or inflammatory changes.In patients with acute cerebellar ataxia, the cerebrospinal fluid tests are normal or may show a pleocytosis with a lymphocytic predominance.

Generally, head imaging, either with computed tomography (CT) or magnetic resonance imaging (MRI), is ordered before the LP to rule out a posterior fossa lesion or hydrocephalus. Most often the head imaging is normal; however, rarely it may show a change in signal in the cerebellum.

Would imaging studies be helpful? If so, which ones?

Imaging studies, particularly head computed tomography (CT) or magnetic resonance imaging (MRI), are not necessary to make the diagnosis; however, as noted above, because acute cerebellar ataxia is a diagnosis of exclusion and often occurs in young children in whom the examination and history can be limited, these studies can be helpful in ruling out other more severe causes of acute ataxia.

Without focal neurologic changes, asymmetric ataxia, or altered mental status, the yield of the image is low. Although there is the risk of radiation exposure, head CT should be sufficient imaging to evaluate for signs of hydrocephalus; however, it is not optimum for evaluating for a posterior fossa lesion. A brain MRI, although costly, does not expose the patient to radiation and would evaluate for both hydrocephalus and posterior fossa lesions.

If you are able to confirm that the patient has acute cerebellar ataxia, what treatment should be initiated?

Once other causes of acute ataxia have been ruled out, the physician can focus on the treatment. This disease is non–life threatening, so no immediate life-saving therapies are necessary. Currently, no pharmacologic therapies have been proved to change the outcome for this disease; therefore it is managed symptomatically.

Depending on the severity of the cerebellar symptoms, a child may benefit from an evaluation and treatment by a physical and/or occupational therapist. Possible treatments that are rarely considered in more chronic or worsening cases of ataxia may include intravenous immunoglobin, corticosteroids, or plasmapheresis. As some children may have behavioral changes or difficulty concentrating, they may also benefit from counseling and focused educational therapies.

What are the adverse effects associated with each treatment option?

The adverse effects with physical and/or occupational therapy are minimal.

What are the possible outcomes of this disease?

The prognosis of recovery from acute cerebellar ataxia is high. More than 90% of all children make a complete recovery in weeks to months after the onset of symptoms. The small percentage of children who do not make a full recovery often have chronic gait abnormalities or imbalance and would continue to benefit from therapy.

What causes this disease and how frequent is it?

Acute cerebellar ataxia is a postinfectious syndrome. It is the most common cause of acute ataxia in young children (approximately 40% of cases). This is a sporadic disease; the incidence is variable.The age distribution most commonly involves children 2-6 years old. The most common infections associated with acute cerebellar ataxia are varicella virus, coxsackievirus, Epstein-Barr virus, echovirus, herpes simplex virus, and Mycoplasma pneumoniae. At this time, there is no known genetic predisposition.

How do these pathogens/genes/exposures cause the disease?

Acute cerebellar ataxia is hypothesized to be an immunoinflammatory reactive process. Although not proved as causal, it is thought that the body develops antineuronal antibodies after the preceding illness, which have a predisposition for the cerebellar system, causing the cerebellar symptoms. There is often evidence of inflammation in the cerebrospinal fluid as demonstrated by pleocytosis.

What complications might you expect from the disease or treatment of the disease?

The complications either from the disease or the therapy (physical and/or occupational therapy) are minimal. If a child’s course does not improve or worsens, a different cause for the cerebellar symptoms should be investigated.